The present invention relates to an optical fibre comprising a plurality of cladding voids, method of producing such a fibre, and use of such a fibre including articles comprising the fibre. More particularly, the present invention relates to an optical fibre having a hermetical sealing of the voids and a method for sealing said voids. By sealing the voids of the fibre according to the present invention the optical fibre may be prepared or optimised for being connected to an optical system, which may include optical fibres and other optical waveguides having optical properties different to the sealed void-containing fibre.